1. Field of the Invention
The present invention relates to a wiring substrate for resin molding and a process for manufacturing a semiconductor device into which this wiring substrate is incorporated.
2. Description of the Related Art
As shown in FIG. 8, a board-on-chip (BOC) type semiconductor device is composed in such a manner that a semiconductor chip 12 is fixed to a semiconductor chip mounting section, which is formed on one face of the resin substrate 10, with adhesive 11. Wiring patterns 13, which are formed on the other face of the resin substrate 10, and a terminal section of the semiconductor chip 12, are electrically connected with each other by a bonding wire 15 inserted into a through-hole (slit) 14 formed on the resin substrate 10. Reference numeral 16 is a ball terminal used for the connection with the outside. This ball terminal 16 is arranged on the wiring pattern 13.
A simple BOC type semiconductor device is known in which the bonding wire 15 and the through-hole 14 are sealed only with potting resin. However, in order to enhance the reliability of the semiconductor device, recently, there has been a demand for a semiconductor device in which both the semiconductor chip 12 and the bonding wire 15 are sealed with the sealing resin 17 by means of transfer molding.
FIG. 9 is a view showing an example of the method of manufacturing the above semiconductor device made by means of transfer molding.
According to this manufacturing method, a large number of semiconductor chips are mounted on a wiring substrate of a predetermined width and molded at one time. After that, the resin-molded wiring substrate is cut off and separated into pieces of individual semiconductor devices.
On one face of the strip-like resin substrate 10 of the wiring substrate 18, there are provided a plurality of rows of semiconductor chip mounting sections, which are arranged in the width direction of the resin substrate 10 by a number of pieces (in the case shown in the drawing, the number of pieces is three), in the longitudinal direction of the resin substrate. In the width direction of the resin substrate 10, for each row of the semiconductor chip mounting sections, one through-hole 14 is arranged. On the other face of the resin substrate 10, the wiring pattern 13 (not shown in FIG. 9) is arranged and is electrically connected with the terminal section of the semiconductor chip 12, and is mounted on the semiconductor chip mounting section, via the bonding wire inserted into the through-hole 14.
The semiconductor chip 12 is fixed to each semiconductor mounting section on the wiring substrate 18 with adhesive. After the terminal section of the semiconductor chip and the wiring pattern are connected with each other by the bonding wire, the wiring substrate 18 is incorporated into a metal mold as shown in FIG. 11.
In the semiconductor chip mounting section on each row, one common through-hole (slit) 14 is formed. Therefore, when the semiconductor chip 12 is mounted in each semiconductor chip mounting section, the through-hole portion 14a not covered with the semiconductor chip 12 exists.
When sealing resin is injected into the metal mold in the direction A shown in the drawing, the injected resin flows from the through-hole portion 14a into the opposite side of the resin substrate 10 (the side on which the wiring pattern is formed) as shown in FIG. 11. Accordingly, it is possible to conduct molding of the sealing resin on both the semiconductor chip 12 and the bonding wire 15 at one time. In this connection, FIG. 11 is a sectional view taken on line axe2x80x94a in FIG. 9, and FIG. 12 is a sectional view taken on line bxe2x80x94b in FIG. 10.
FIG. 10 is a view showing another manufacturing method. According to this manufacturing method, there is provided an independent through-hole (slit) 14 for each semiconductor chip mounting section. The length of this through-hole 14 is determined so that a portion 14a, which is not covered with the semiconductor chip 12 to be mounted, can be generated.
When the wiring substrate 18 is incorporated into the metal mold as shown in FIG. 12 and sealing resin is injected in the direction A shown in the drawing, the injected resin flows from the through-hole portion 14a into the opposite side of the resin substrate 10 as shown in FIG. 12. Therefore, it is possible to conduct resin sealing on both the semiconductor chip 12 and the bonding wire 15 at the same time.
However, the following problems may be encountered in the above-mentioned conventional method of manufacturing the semiconductor device.
As shown in FIGS. 11 and 12, in either of the above manufacturing method, sealing resin simultaneously flows into the opposite side of the resin substrate 10 via the through-hole portion 14a. Therefore, by the pressure of resin which has flowed onto the wiring pattern forming side of the resin substrate 10 from the through-hole portion 14a, there is a tendency that the resin substrate 10 is pushed up. This is a disadvantageous aspect in this method of molding resin.
Due to the foregoing, sealing resin flows out between the resin substrate 10 and the metal mold parting face. Therefore, problems of leakage and a burr of the sealing resin are caused.
Since solvent is mixed in the sealing resin, even when the resin substrate is a hardly raised, the solvent bleeds onto the wiring pattern 13 and deposits on the formation face of the ball terminal 16, which becomes an obstacle to the fixation of the ball terminal 16.
The present invention has been accomplished to solve the above-mentioned problems.
An object of the present invention is to provide a method of manufacturing a semiconductor device capable of preventing leakage of resin, generation of burr and bleeding of solvent.
Another object of the present invention is to provide a wiring substrate preferably applied to the method of manufacturing the semiconductor device.
According to an aspect of the present invention, there is provided a wiring board adapted to be used for making a resin-molded type semiconductor device, said wiring board comprising: an insulating substrate having first and second surfaces, a plurality of semiconductor chip mounting sections arranged one by one along a predetermined direction on said first surface extending from one end to the other end of the substrate, and a resin transmitting port opened at said first and second surfaces of the substrate and penetrating therethrough, said resin transmitting port being located at a position in the vicinity of said one end along said predetermined direction and other than the semiconductor chip mounting section arranged nearest to said one end.
The substrate further has a plurality of through holes within the respective semiconductor chip mounting sections, in such a manner that, when a semiconductor chip is mounted on the semiconductor chip mounting section of the substrate, said through hole is completely covered by said semiconductor chip at the first surface and terminals of the semiconductor chip are exposed within said through hole.
The respective semiconductor chip mounting sections are all the same size and one equidistantly arranged along said predetermined direction.
The insulating substrate is a longitudinal strip-like resin sheet and said one direction is a width direction of the longitudinal sheet.
According to another aspect of the present invention, there is provided a wiring board adapted to be used for making a resin-molded type semiconductor device, said wiring board comprising an insulating substrate having first and second surfaces, a plurality of semiconductor chip mounting sections arranged one by one along a predetermined direction on said first surface extending from one end to the other end of the substrate, and a resin transmitting port opened at said first and second surfaces of the substrate and penetrating therethrough, said resin transmitting port being located at a position in the vicinity of said one end along said predetermined direction and other than the semiconductor chip mounting section arranged nearest to said one end, a plurality of through holes within the respective semiconductor chip mounting sections, in such a manner that, when a semiconductor chip is mounted on the semiconductor chip mounting section, said through hole is completely covered by said semiconductor chip at the first surface and terminals of the semiconductor chip are exposed within said through hole; and wiring patterns formed on said second surface of the substrate in such a manner that, after a semiconductor chip is mounted on the semiconductor chip mounting section, said terminals of the semiconductor chip can be electrically connected to the wiring patterns by means of bonding wires passing through said through hole.
According to further aspect of the present invention, there is provided a process for making a semiconductor device comprising the following steps of:
preparing an insulating substrate having first and second surfaces, a plurality of semiconductor chip mounting sections arranged one by one along a predetermined direction on said first surface extending from one end to the other end of the substrate, and a resin transmitting port opened at said first and second surfaces of the substrate and penetrating therethrough, said resin transmitting port being located at a position in the vicinity of said one end along said predetermined direction and other than the semiconductor chip mounting section arranged nearest to said one end;
mounting a semiconductor chip on a respective semiconductor chip mounting section;
setting a mold so as to define a cavity including first and second cavity sections on said first and second surfaces of the substrate, respectively, in such a manner that said first and second cavities communicate with each other by means of said resin transmitting port;
injecting a sealing resin into said cavity, so that said resin flows through said resin transmitting port to fill both of said first and second cavity sections with the sealing resin.
The sealing resin is injected into said cavity through a gate located in the vicinity of said other end of the substrate.
The semiconductor chip is mounted on said respective semiconductor chip mounting section by means of adhesive.
The mold comprises a first and second mold sections so as to nip said substrate from said first and second surfaces thereof, respectively, to define said first and second cavity sections on said first and second surfaces of the substrate, respectively.
The sealing resin is injected into the cavity through a gate provided in one of the first and second mold sections and located in the vicinity of the other end of the substrate, in such a manner that the one of the cavity sections is first filled with resin and then the other of said cavity sections is filled with resin.
The substrate preparing step further comprising the following steps of: forming a plurality of through holes within the respective semiconductor chip mounting sections; and forming wiring patterns on said second surface of the substrate; and wherein
said semiconductor chip mounting step further comprising the following steps of: completely covering said through hole with said semiconductor chip at the first surface and exposing terminals of the semiconductor chip within said through hole; and electrically connecting said terminals of the semiconductor chip to the wiring patterns by means of bonding wires passing through said through hole.
According to further aspect of the present invention, there is provided a resin-molded type semiconductor device, said wiring board comprising:
an insulating substrate having first and second surfaces, a plurality of semiconductor chip mounting sections arranged one by one along a predetermined direction on said first surface extending from one end to the other end of the substrate, and a resin transmitting port opened at said first and second surfaces of the substrate and penetrating therethrough, said resin transmitting port being located at a position in the vicinity of said one end along said predetermined direction and other than the semiconductor chip mounting section arranged nearest to said one end, a plurality of through holes within the respective semiconductor chip mounting sections, in such a manner that;
wiring patterns formed on said second surface of the substrate;
a semiconductor chip mounted on the semiconductor chip mounting section, in such a manner that said through hole is completely covered by said semiconductor chip at the first surface and terminals of the semiconductor chip are exposed within said through hole;
bonding wires passing through said through hole for electrically connecting terminals of the semiconductor chip to said wiring patterns; and
a sealing resin for sealing at least said semiconductor chip, said wiring patterns and said bonding wires.